The present invention relates to miniature current overload fuses which, whether they are rated to carry only a few amperes or as much as 30 amperes, occupy a space which is only a fraction of the space occupied by the conventional glass envelope cylindrical fuses.
A marked improvement in overload current fuses having a rating of from 10-30 amperes has been made where the fuse has a length well under 3/4 inch and a width of under 1/4 inch. Such a fuse is disclosed in U.S. Pat. No. 3,436,711. Also, the terminals of the improved fuses plug into socket openings transversely to the length of the fuse body, so the socket connector can be a much less expensive and less bulky support means than that needed for conventional high current rated fuses.
While the miniature fuses heretofore developed have been a substantial improvement over the conventional cylindrical glass envelope fuses, they still left much to be desired from the standpoint of their cost of manufacture and protection to the user. For example, in some of the miniature fuses heretofore developed, the fuse link was exposed so that the insertion thereof into a shorted circuit would blow the same and spew fuse material onto the person inserting the fuse. Also, it was possible for a person inserting or removing such a fuse to make contact with the exposed fuse link which created a shock hazard if he engaged the fuse negligently. While in one form of miniature fuse heretofore developed, as for example, that disclosed in U.S. Pat. No. 3,775,723, the fuse link was enclosed in a transparent housing having a handle extending from the outer walls thereof, the fuse was relatively expensive to manufacture and it had less reliability than the fuse of the present invention.
It is, accordingly, one of the objects of the invention to provide a method of making a miniature fuse with an enclosed fuse link and which is capable of carrying currents where desired well in excess of 10 amperes, such as up to 30 amperes, and can be manufactured at a much smaller cost than the miniature fuses heretofore designed.
A related object of the invention is to provide a method of making a miniature fuse having a housing providing an insulated gripping surface and a shield protecting the user from being contacted by the fuse material as an inserted fuse is blown.
In most of the miniature fuse designs heretofore proposed, the terminals have cylindrical pin-like configurations molded into bases of insulating material, and the fuse links were soldered between the inner ends of these terminals. The presence of solder connections sometimes created problems of reliability resulting from corrosion or hot spots due to poor solder connections or deterioration with age. Thus, another object of the present invention is to provide a method of making a miniature fuse having features satisfying one or more of the objectives previously discussed and, in addition, are devoid of the corrosion or hot spot problems referred to.